@size: 160px;
@minu: 40px;

body {
  padding: 120px;
}

.wrap {
  position: relative;
  width: @size;
  height: @size;
  margin: auto;
}

.wrap > div {
  position: absolute;
}

.class1 {
  background-color: #f00;
  clear: both;
  height: @size;
  width: @size;
  top: 0;
  left: 0;
}

.class2 {
  background-color: #0f0;
  clear: both;
  height: @size - @minu;
  width: @size - @minu;
  top: (@minu / 2);
  left: (@minu / 2);
}

.class3 {
  background-color: #00f;
  clear: both;
  height: @size - @minu*2;
  width: @size - @minu*2;
  top: @minu;
  left: @minu;
}
